Implement model-to-screen space transformations

Makefile

@@ -36,10 +36,10 @@ WARNINGS_OFF=-Wno-missing-braces -Wno-gnu-anonymous-struct -Wno-old-style-cast\
 CFLAGS=$(D) $(O) -std=c++11 $(WARNINGS_ON) $(WARNINGS_OFF) -I$(INCLUDE_DIR)
 LIBS=-lSDL2
 
-_HEADERS = engine.h loader.h geometry.h platform.h point.h util.h
+_HEADERS = engine.h geometry.h loader.h platform.h point.h transform.h util.h
 HEADERS = $(patsubst %,$(INCLUDE_DIR)/%,$(_HEADERS))
 
-_OBJS = engine.o loader.o main.o platform.o
+_OBJS = engine.o loader.o main.o platform.o transform.o
 OBJS = $(patsubst %,$(BUILD_DIR)/%,$(_OBJS))
 
 $(BUILD_DIR)/%.o: $(SRC_DIR)/%.cpp $(HEADERS)

include/camera.h

@@ -0,0 +1,45 @@
+#ifndef CAMERA_H
+
+#include "point.h"
+#include "util.h"
+#include <cmath>
+
+
+// STRUCTURE
+struct Camera
+{
+    inline Camera(void)
+    {
+        position.x = 0.0f;
+        position.y = 0.0f;
+        position.z = 0.0f;
+
+        rotation[0] = 0.0f;
+        rotation[1] = 0.0f;
+        rotation[2] = 0.0f;
+
+        nearClip = 1.0f;
+        farClip = 1000.0f;
+    }
+
+    inline void SetFOV(float fov, int winWidth, int winHeight)
+    {
+        xZoom = 1.0f / tanf(DEG_TO_RAD(fov/2.0f));
+        yZoom = (xZoom * winWidth) / winHeight;
+
+        xScale = (0.5f * winWidth) - 0.5f;
+        yScale = (0.5f * winHeight) - 0.5f;
+    }
+
+
+    Point position;
+    float rotation[3];
+    float nearClip, farClip;
+    float xZoom, yZoom;
+    float xScale, yScale;
+};
+
+
+#define CAMERA_H
+#endif
+

include/engine.h

@@ -33,7 +33,7 @@ struct Engine_Buffer
 
 
 // FUNCTIONS
-int Engine_Init(char *filename);
+int Engine_Init(Engine_Buffer &buffer, char *filename);
 void Engine_Render(Engine_Buffer &buffer, uint32_t input);
 void Engine_Shutdown(void);
 

include/geometry.h

@@ -11,7 +11,24 @@ struct Face
 
 struct Mesh
 {
+    inline Mesh(void)
+    {
+        position.x = 0.0f;
+        position.y = 0.0f;
+        position.z = 0.0f;
+
+        rotation[0] = 0.0f;
+        rotation[1] = 0.0f;
+        rotation[2] = 0.0f;
+
+        scale = 1.0f;
+    }
+
+    Point position;
+    float rotation[3];
+    float scale;
     std::vector<Point> verts;
+    std::vector<Point> vertsTransformed;
     std::vector<Face> faces;
 };
 

include/matrix.h

@@ -0,0 +1,80 @@
+#ifndef MATRIX_H
+
+
+#include "point.h"
+
+
+// STRUCTURE
+struct Matrix
+{
+    inline Matrix(void)
+    {
+        e11 = 1.0; e12 = 0.0; e13 = 0.0; e14 = 0.0;
+        e21 = 0.0; e22 = 1.0; e23 = 0.0; e24 = 0.0;
+        e31 = 0.0; e32 = 0.0; e33 = 1.0; e34 = 0.0;
+        e41 = 0.0; e42 = 0.0; e43 = 0.0; e44 = 1.0;
+    }
+
+    union
+    {
+        float e[4][4];
+
+        struct
+        {
+            float e11, e12, e13, e14;
+            float e21, e22, e23, e24;
+            float e31, e32, e33, e34;
+            float e41, e42, e43, e44;
+        };
+    };
+};
+
+
+// OPERATORS
+// m1 * m2
+inline Matrix operator*(Matrix m1, Matrix m2)
+{
+    Matrix result;
+
+    for (int row = 0; row < 4; ++row)
+    {
+        for (int col = 0; col < 4; ++col)
+        {
+            float sum = 0.0;
+
+            for (int i = 0; i < 4; ++i)
+            {
+                sum += m1.e[row][i] * m2.e[i][col];
+            }
+
+            result.e[row][col] = sum;
+        }
+    }
+
+    return result;
+}
+
+// v * m
+inline Point operator*(Point v, Matrix m)
+{
+    Point result;
+
+    for (int col = 0; col < 4; ++col)
+    {
+        float sum = 0.0;
+
+        for (int row = 0; row < 4; ++row)
+        {
+            sum += v.e[row] * m.e[row][col];
+        }
+
+        result.e[col] = sum;
+    }
+
+    return result;
+}
+
+
+#define MATRIX_H
+#endif
+

include/point.h

@@ -19,6 +19,22 @@ struct Point
 };
 
 
+// OPERATORS
+// v / f
+inline Point operator/(Point v, float f)
+{
+    Point result;
+
+    float inverse = 1.0f / f;
+
+    result.x = v.x * inverse;
+    result.y = v.y * inverse;
+    result.z = v.z * inverse;
+
+    return result;
+}
+
+
 #define POINT_H
 #endif
 

include/transform.h

@@ -0,0 +1,17 @@
+#ifndef TRANSFORM_H
+
+
+#include "matrix.h"
+
+
+Matrix Transform_Translate(float x, float y, float z);
+Matrix Transform_Rotate(float x, float y, float z);
+Matrix Transform_Scale(float s);
+Matrix Transform_View(Point &position, float rotation[]);
+Matrix Transform_Perspective(float zoomX, float zoomY, float nearClip, float farClip);
+Matrix Transform_Screen(float xScale, float yScale);
+
+
+#define TRANSFORM_H
+#endif
+

include/util.h

@@ -1,10 +1,19 @@
 #ifndef UTIL_H
 
+#include <cmath>
+
+
+// CONSTANTS
+const float EPSILON_E3 = 1E-3f;
+
 
 // MACROS
 #define SET_BIT(x, bit) (x |= (1UL << bit))
 #define CLEAR_BIT(x, bit) (x &= ~(1UL << bit))
 #define CHECK_BIT(x, bit) (x & (1UL << bit))
+#define DEG_TO_RAD(deg) ((deg * (float)M_PI) / 180.0f)
+#define SWAP(a, b, temp) {temp = a; a = b; b = temp;}
+#define FLOAT_EQUAL(a, b) ((fabsf(a - b) < EPSILON_E3) ? 1 : 0)
 
 
 #define UTIL_H

src/engine.cpp

@@ -1,12 +1,23 @@
+#include "camera.h"
 #include "engine.h"
 #include "loader.h"
+#include "matrix.h"
+#include "transform.h"
+#include "util.h"
+#include <cstdio>
 
 
 // GLOBALS
 static Mesh mesh;
+static Camera camera;
 
 
-int Engine_Init(char *filename)
+// PRIVATE PROTOTYPES
+static void CheckInputs(uint32_t input);
+
+
+// PUBLIC FUNCTIONS
+int Engine_Init(Engine_Buffer &buffer, char *filename)
 {
     int result = LoadMesh(filename, mesh);
 
@@ -15,14 +26,124 @@ int Engine_Init(char *filename)
         return -1;
     }
 
+    mesh.position.z = 250;
+
+    camera.SetFOV(90.0f, buffer.width, buffer.height);
+
     return 0;
 }
 
 void Engine_Render(Engine_Buffer &buffer, uint32_t input)
 {
+    CheckInputs(input);
+
+    Matrix tTranslate = Transform_Translate(
+            mesh.position.x, mesh.position.y, mesh.position.z);
+
+    Matrix tRotate = Transform_Rotate(
+            mesh.rotation[0], mesh.rotation[1], mesh.rotation[2]);
+
+    Matrix tScale = Transform_Scale(
+            mesh.scale);
+
+    Matrix tView = Transform_View(
+            camera.position, camera.rotation);
+
+    Matrix tPersp = Transform_Perspective(
+            camera.xZoom, camera.yZoom, camera.nearClip, camera.farClip);
+
+    for (size_t v = 0; v < mesh.verts.size(); ++v)
+    {
+        mesh.vertsTransformed[v] =
+            mesh.verts[v] * tScale * tRotate * tTranslate * tView * tPersp;
+
+        mesh.vertsTransformed[v] =
+            mesh.vertsTransformed[v] / mesh.vertsTransformed[v].w;
+    }
+
+    Matrix tScreen = Transform_Screen(camera.xScale, camera.yScale);
+
+    for (size_t v = 0; v < mesh.verts.size(); ++v)
+    {
+        mesh.vertsTransformed[v] = mesh.vertsTransformed[v] * tScreen;
+    }
+
+    for(size_t f = 0; f < mesh.faces.size(); ++f)
+    {
+        unsigned int v0 = mesh.faces[f].vertIndex[0];
+        unsigned int v1 = mesh.faces[f].vertIndex[1];
+        unsigned int v2 = mesh.faces[f].vertIndex[2];
+    }
 }
 
 void Engine_Shutdown(void)
 {
 }
 
+
+// PRIVATE FUNCTIONS
+static void CheckInputs(uint32_t input)
+{
+    if (CHECK_BIT(input, TRANSLATE_X_POS))
+    {
+        mesh.position.x += 10;
+    }
+    else if (CHECK_BIT(input, TRANSLATE_X_NEG))
+    {
+        mesh.position.x -= 10;
+    }
+
+    if (CHECK_BIT(input, TRANSLATE_Z_POS))
+    {
+        mesh.position.z += 10;
+    }
+    else if (CHECK_BIT(input, TRANSLATE_Z_NEG))
+    {
+        mesh.position.z -= 10;
+    }
+
+    if (CHECK_BIT(input, TRANSLATE_Y_POS))
+    {
+        mesh.position.y += 10;
+    }
+    else if (CHECK_BIT(input, TRANSLATE_Y_NEG))
+    {
+        mesh.position.y -= 10;
+    }
+
+    if (CHECK_BIT(input, ROTATE_X_POS))
+    {
+        mesh.rotation[0] += .10;
+    }
+    else if (CHECK_BIT(input, ROTATE_X_NEG))
+    {
+        mesh.rotation[0] -= .10;
+    }
+
+    if (CHECK_BIT(input, ROTATE_Z_POS))
+    {
+        mesh.rotation[1] += .10;
+    }
+    else if (CHECK_BIT(input, ROTATE_Z_NEG))
+    {
+        mesh.rotation[1] -= .10;
+    }
+
+    if (CHECK_BIT(input, ROTATE_Y_POS))
+    {
+        mesh.rotation[2] += .10;
+    }
+    else if (CHECK_BIT(input, ROTATE_Y_NEG))
+    {
+        mesh.rotation[2] -= .10;
+    }
+
+    if (CHECK_BIT(input, SCALE_UP))
+    {
+        mesh.scale += 0.1f;
+    }
+    else if (CHECK_BIT(input, SCALE_DOWN))
+    {
+        mesh.scale -= 0.1f;
+    }
+}

src/loader.cpp

@@ -67,6 +67,8 @@ int LoadMesh(char *filename, Mesh &mesh)
     printf("Verts: %lu\n", mesh.verts.size());
     printf("Faces: %lu\n", mesh.faces.size());
 
+    mesh.vertsTransformed.resize(mesh.verts.size());
+
     fclose(fp);
 
     return 0;

src/main.cpp

@@ -6,8 +6,8 @@
 
 
 // CONSTANTS
-const unsigned int WINDOW_WIDTH = 800;
+const unsigned int WINDOW_WIDTH = 1920;
-const unsigned int WINDOW_HEIGHT = 600;
+const unsigned int WINDOW_HEIGHT = 1080;
 const unsigned int WINDOW_FPS = 30;
 
 
@@ -33,7 +33,7 @@ int main(int argc, char *argv[])
         buffer.width = platform.surface->w;
         buffer.height = platform.surface->h;
 
-        result = Engine_Init(filename);
+        result = Engine_Init(buffer, filename);
 
         if (result < 0)
         {

src/transform.cpp

@@ -0,0 +1,104 @@
+#include "matrix.h"
+#include "transform.h"
+#include <cmath>
+
+
+// PUBLIC FUNCTIONS
+Matrix Transform_Translate(float x, float y, float z)
+{
+    Matrix result;
+
+    result.e41 = x;
+    result.e42 = y;
+    result.e43 = z;
+
+    return result;
+}
+
+Matrix Transform_Rotate(float x, float y, float z)
+{
+    // YXZ Euler rotation
+    float cosThetaY = cosf(y);
+    float sinThetaY = sinf(y);
+
+    Matrix tRotateY;
+
+    tRotateY.e11 = cosThetaY;
+    tRotateY.e13 = -sinThetaY;
+    tRotateY.e31 = sinThetaY;
+    tRotateY.e33 = cosThetaY;
+
+
+    float cosThetaX = cosf(x);
+    float sinThetaX = sinf(x);
+
+    Matrix tRotateX;
+
+    tRotateX.e22 = cosThetaX;
+    tRotateX.e23 = sinThetaX;
+    tRotateX.e32 = -sinThetaX;
+    tRotateX.e33 = cosThetaX;
+
+
+    float cosThetaZ = cosf(z);
+    float sinThetaZ = sinf(z);
+
+    Matrix tRotateZ;
+
+    tRotateZ.e11 = cosThetaZ;
+    tRotateZ.e12 = sinThetaZ;
+    tRotateZ.e21 = -sinThetaZ;
+    tRotateZ.e22 = cosThetaZ;
+
+
+    Matrix result = tRotateY * tRotateX * tRotateZ;
+
+    return result;
+}
+
+Matrix Transform_Scale(float s)
+{
+    Matrix result;
+
+    result.e11 = s;
+    result.e22 = s;
+    result.e33 = s;
+
+    return result;
+}
+
+Matrix Transform_View(Point &position, float rotation[])
+{
+    Matrix tInvTranslate = Transform_Translate(-position.x, -position.y, -position.z);
+
+    Matrix tInvRotate = Transform_Rotate(-rotation[0], -rotation[1], -rotation[2]);
+
+    Matrix result = tInvTranslate * tInvRotate;
+
+    return result;
+}
+
+Matrix Transform_Perspective(float zoomX, float zoomY, float nearClip, float farClip)
+{
+    Matrix result;
+
+    result.e11 = zoomX;
+    result.e22 = zoomY;
+    result.e33 = (farClip + nearClip) / (farClip - nearClip);
+    result.e34 = 1;
+    result.e43 = (-2.0f * farClip * nearClip) / (farClip - nearClip);
+
+    return result;
+}
+
+Matrix Transform_Screen(float xScale, float yScale)
+{
+    Matrix result;
+
+    result.e11 = xScale;
+    result.e41 = xScale;
+    result.e22 = -yScale;
+    result.e42 = yScale;
+
+    return result;
+}